O032 Neuromodulation to enhance sleep and cognition in healthy older adults

Abstract Introduction Ageing is associated with cognitive decline and altered sleep architecture including greater sleep fragmentation. Alterations in brain oscillations such as decreased slow wave activity (SWA) and sleep spindles, which are important for cognition, are observed. Slow oscillatory transcranial direct current stimulation (so-tDCS) has been used as an intervention to enhance slow wave sleep (SWS) and indirectly boost memory. However, studies showed inconsistent stimulation effects on sleep and cognition and were limited by conventional so-tDCS methods that delivered stimulation to broad areas of the frontal brain regions. The emergence of high-definition so-tDCS allows for a more accurate delivery of the current flow to targeted and distinct brain areas. Therefore, this current proof-of-concept study aimed to 1) evaluate the technical feasibility of delivering brain stimulation during sleep using high-definition so-tDCS montages to target two distinct brain regions – frontal and parietal, and to 2) test the effects of the stimulation on sleep EEG activity and cognition. Methods Five healthy participants, aged 40 to 65 years were recruited for this randomised, sham-controlled, single-blinded, crossover pilot study. Three randomised visits, two active and one sham stimulation sessions were conducted with a 1-day washout. Results The protocol was feasible, acceptable and tolerable. Participants were successfully blinded. Visual inspection of topographies revealed increase in SWA for both active vs sham comparisons. Discussion This research provides insight into the feasibility of this innovative protocol and will inform a larger trial assessing the effects of neuromodulation on sleep and cognition in ageing.